The present invention relates to a drying machine which can estimate a time required for a drying operation.
In a typical drying machine, a user operates a timer to set a drying operation time, and after the drying operation time has elapsed, the drying operation is ended. In contrast to this, in some recent drying machines, the machine can detect that clothes in a drying chamber have attained a predetermined degree of dryness and the machine then automatically completes the drying operation. However, in this drying machine, since the user cannot determine when the drying operation is completed, clothes are often left in the drying chamber, in which waste heat still remains, and the clothes therein become wrinkled.
A technique for eliminating this drawback is described in Japanese Patent Publication No. 60-48198 entitled "DRYING MACHINE", the inventor: Miwa, the filing date: Apr. 28, 1979. This patent discloses a drying machine which includes a remaining time estimating device for detecting the rate of increase in exhaust temperature and for estimating a remaining time of a drying operation based on the detection result and prestored estimated remaining time data, a remaining time determination device for detecting the degree of dryness of clothes to be dried to determine the remaining time of the drying operation, and a display device for displaying the respective time data and a stop period time display which is formed between the respective time displays. Japanese Utility Model Disclosure No. 55-153097 entitled "DRYING MACHINE", the inventor: Yamauchi, the filing date: Apr. 23, 1979, on the other hand, discloses a drying machine which includes a temperature detector for detecting the rate of increase in exhaust temperature from the drying machine at the beginning of the drying operation, a remaining time estimating device for estimating a remaining time of the drying operation in accordance with the rate of increase in exhaust temperature, and a display device for displaying the estimated time. Also, Japanese Utility Model Disclosure No. 60-27896 entitled "VOLUME OF CLOTHES DETECTING DEVICE FOR DRYING MACHINE", the inventor: Hotta, the filing date: July 29, 1983, discloses a volume-of-clothes detecting device which comprises a pulse generator, having an electrode, which contacts clothes to be dried in a rotary chamber, for generating a pulse upon contacting of the clothes, and a discriminating device for discriminating a pulse generation frequency of the pulse generator.
More specifically, a temperature sensor for detecting an exhaust temperature from the drying chamber is provided to detect an exhaust temperature from the drying chamber at the beginning of the drying operation, thereby measuring the rate of increase in exhaust temperature. A time required for the drying operation is estimated in accordance with the rate of increase in exhaust temperature, and the estimated time data is displayed on the display device. The time required for the drying operation is estimated in accordance with the inventor's experiences such that if the exhaust temperature increases slowly at the beginning of the drying operation, the period is prolonged.
With this arrangement, the user can determine an approximate time required for the drying operation at the beginning of the drying operation by referring to the display device. Therefore, if the user leaves the area and later returns to the drying machine when the drying operation should be ended, he or she can pick up dried clothes from the drying chamber, resulting in convenience to the user.
However, the aforementioned arrangement still has the following drawbacks.
Since the heat capacity of wet clothes is considerably large, it takes a long period of time until the exhaust temperature increases. Therefore, in order to obtain a practical measurement precision, 10 to 20 minutes are required. For this reason, the user cannot confirm an estimated time until 10 to 20 minutes has elapsed from the beginning of the drying operation, and must wait until the estimated time data is displayed. Therefore, an estimation function cannot be effectively used.
For example, if washing is performed with hot water, since clothes put into the drying chamber are warm from the beginning, the exhaust temperature is increased too early, and an estimated time is considerably different from a time required for an actual drying operation. With this estimation method, an estimated value is influenced by ambient temperature, humidity, a power supply voltage, and the like, and estimation precision cannot be sufficiently improved.